The present invention relates to a microprocessor and, more particularly, to improvements in the external bus interface of a microprocessor.
There are microprocessors (micro-controllers) equipped with an external bus capable of being directly connected to various semiconductor memories including a synchronous DRAM (dynamic random access memory). Such microprocessors are discussed illustratively in Nikkei Electronics published by Nikkei-MacGrow-Hill, Inc. (Feb. 14, 1994, pp. 79-91).
So-called PC cards such as memory cards and I/O cards are now in widespread use. The conditions for interfacing the PC cards to microprocessors and the like have been standardized by the Japan Electronics Industry Development Association (JEIDA) and the Personal Computer Memory Card International Association ("PCMCIA," which is believed to be a trademark of the Personal Computer Memory Card International Association) The PC card interface includes the IC memory card and I/O card interface provisions for the 68-pin type, stipulated in "6. Electrical Interface Specifications" of the Guideline Ver. 4.1. The PC card interface is implemented illustratively by use of a dedicated integrated circuit (IC) chip such as the 82365SL.